Identification of Inbred Lines as a Source of New Alleles for Improvement of Elite Maize Single Crosses
The identification of inbred lines as sources of favorable alleles not already present in an elite single cross is an important part of the pedigree maize (Zea mays L.) breeding program. The objectives of this study were to identify lines for improvement of elite hybrids. A diallel set of 15 maize inbred lines, which included eight USA (US) public and seven Maize Research Institute “Zemun Polje”, Yugoslavia, proprietary lines were evaluated in 1986 and 1987 in Yugoslavia. Seven hybrids representing Stiff Stalk Synthetic (SSS) ✕ Lancaster, SSS ✕ other US, SSS ✕ Yugoslavian (YU), Lancaster ✕ other US, Lancaster ✕ YU, other US ✕ YU, and YU ✕ YU heterotic patterns were designated as targets for improvement. Significant differences in grain yield were found among lines in minimally biased estimates (μG) of favorable alleles present in a donor inbred, but not present in a recipient hybrid, minimum upper bound (UBND) estimate and predicted threeway performance (PTC) each of the seven hybrids were designated as a target. The highest values for all estimators of new favorable alleles were found for donor lines that belonged to a different heterotic group than the parents of the target hybrid. In most cases (C+F)-(D+E) values agreed with expectation based on pedigree information. Simultaneous increases in yield and decreases in grain moisture appear to be possible for most target hybrids. Correlations among three estimators of new favorable alleles were high, positive, and significant. The highest correlations, which frequently exceeded 0.95, were found between μG and PTC indicating that PTC also provides reliable information.
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